On paper our midfield is all set. However, in reality when it even struggles against teams like Las Palmas and Levante, it says something about the state of it.
A good midfield supports MSN and provides cover for our defense. Right now it is often lacking in both department. Moreover, I wish we could have someone like Gundogan who will adjust the pace and stabilize things.
We have almost always struggle with midfield control in away games against teams that play high pressure on our backline and Busquets. At least until opponents gets tired after good 60 minutes and then we usually punish them.
I think both Rafinha and Denis Suarez are "two-way" midfielders. They will get new fresh blood and creative sparks to our midfield and they are both also good in defensive tasks as they are still young and can run a lot. And I believe Arda will also get better in his second season when he's fully integrated into our system.
But we'll probably never have a total midfield domination like we had in best Xavi and Iniesta days no matter who we buy. First off, because we'll never have two as complete CMs (together with a genius DM like Busquets and GOAT Messi) for possesion based football and second because Lucho's system doesn't depend on midfield creativity as much anymore. Maybe in 3 or 4 years if Xavi comes back as a coach (but I hope he won't really go back to a total tiki-taka style and will keep some of the good things that Lucho has implemented) we'll need a player like Verratti and we'll pay 80M or more for him (he'll most likely still be in PSG and I don't think his price will change much anyway so from financial standpoint it doesn't matter much when we buy him), but right now I don't think we need a midfielder like him. And maybe we won't even need him in the future if some of our young players (Rafinha, Roberto, Suarez, Samper, Alena, Halilovic, Kaptoum,...) will develop good and/or if we manage to find some younger and cheaper alternative on the market. That's why I would like us to continue with the politics of bringing in talented youngsters like Denis and Alen. And of course also younger ones to keep them developing in La Masia.